During the past 25 years significant advances have been made in correcting dentofacial malrelations through a combination of surgery and orthodontics. These interventions have become relatively common; however, there are controversies regarding the various procedures. Current knowledge is based primarily upon case reports and retrospective comparisons. There have been no large randomized clinical trials to establish efficacy, to determine risk factors, nor to establish the cost-effectiveness of specific procedures. The objective of this research is to compare the efficacy and cost-effectiveness of the two most commonly used surgical stabilization procedures--rigid fixation and wire fixation--in the most common orthognathic procedure--mandibular advancement. A secondary objective is to identify patient risk factors and describe the complications associated with these two procedures. These objectives will be accomplished through a randomized clinical trial involving three sites: The University of Texas Health Science Center at San Antonio, Emory University in Atlanta, and the University of Florida at Gainesville. One hundred and eighty patients referred by orthodontists for surgical correction of a Class II dentofacial malrelation will be randomly assigned to receive either rigid or wire fixation. The two patient groups will be assessed before surgery and at five post-surgical intervals over a two-year follow-up period. Assessments will be made of stability, oral function, neurosensory loss, TM signs and symptoms, quality of life, patient satisfaction, and cost-effectiveness. These outcome assessments will be accomplished and scored by evaluators who are blind to the treatment. Specific hypotheses will be tested between groups and the use of standardized assessments will allow us to describe and compare our patients pre- and post-surgery. The trial will have statistical power greater than 0.90 to detect clinically significant differences between the two procedures. The trial includes rules for stopping and interim analyses. A trial review and safety committee will evaluate progress at yearly intervals over the planned five-year study. The knowledge gained from this clinical trial will allow clinicians to appropriately advise patients about the relative efficacy, complications, and cost-effectiveness of these common orthognathic procedures. The results will also provide the necessary knowledge to identify patients at risk for complications with either surgical technique. The long-term objective is to improve oral health care and overall quality of life of persons having dentofacial malrelations.